1. Field of the Invention
This invention relates to new and useful improvements in desilters for drilling muds and more particularly to improve hydrocyclones for separating large particles from drilling muds.
2. Brief Description of the Prior Art
Desilting of drilling muds is a necessary step in the preparation of satisfactory muds for the drilling of oil and gas wells. Desilting consists of removing coarse or large particles from a drilling mud so that the remainder of the mud is of a more uniform particle size. The need for desilting and some of the methods of desilting are set forth in papers by George S. Ormsby entitled, "How Proper Desilting Helps in Unweighted Mud Drilling", and "Correction of Common Errors in Drilled Solids Removal Systems."
Desilting, or removal of coarse or large size particles, of drilling muds is commonly accomplished by the use of hydrocyclone separators. Some basic theory on design and operation of hydrocyclones is set forth in "Theory, Applications and Practical Operation of Hydrocyclones", Trawinski, E-MJ-September, 1976; and "Solid-Liquid/Liquid-Liquid Separation Equipment--Centrifuges, Cyclones, Settlers", paper presented at the National AICHE Meeting/Petrochemical and Refining Exposition, Houston, Tex.--Mar. 1-4, 1971.
Several U.S. patents disclose hydrocyclone separators having certain controlled features.
Trawinski, U.S. Pat. No. 3,817,388, discloses hydrocyclone separators having valves controlling the input to the hydrocyclones from a central reservoir and having separate collection systems for the overflow and underflow from the separator.
Zemanek, U.S. Pat. No. 3,764,005, discloses a hydrocyclone separator for pulp in which there are provided valves controlling the input flow and the overflow and a valve controlling the introduction of air into the outlet zone from the separator.
Carr, U.S. Pat. No. 3,568,847, discloses a hydrocyclone separator having an inflatable restriction in the overflow line to control the overflow from the hydrocyclone.